The microelectronic triode is a device which is fairly well known in the prior art. Such a device combines optimized solid state and vacuum tube capabilities. Essentially, the triode operates as a vacuum tube triode but utilizes integrated circuit techniques for fabrication. Such devices are required for microwave frequency applications requiring fairly large power, such as in the utilization of active antenna arrays in electronic countermeasures, radar and communications systems.
Vacuum microelectronic triodes have been described which operate up to 300 GHz and have been widely discussed in the literature. See, for an example, an article entitled "Frequency Limits of Electronic Tubes with Field Emission Cathodes" by W. A. Anderson published at the Second International Conference on Vacuum Microelectronics, Bath, 1989. See also a publication entitled "A Wide Bandwidth, High Gain Small Sized Distributed Amplifier with Field Emission Triodes (FETRODES) for the 10 to 300 GHz Frequency Range" by H. G. Kosmahl, IEEE Transactions on Electron Devices, Vol. 36, No. 11, Nov. 1989. See also an article entitled "An X-Band Tuned Amplifier with a Field-Emission Cathode" by P. M. Lally, Y. Goren, E. A. Netteshein, published in the IEEE Transactions on Electron Devices, Vol. 36, No. 11, Nov. 1989.
As indicated, these devices are based on conventional vacuum tube triode operation but are fabricated utilizing integrated circuit techniques. Such devices employ a lateral topology with strip line interconnects or a vertical scheme that places many triodes in parallel or in series. The parallel outputs combine to increase the overall current available from a single field emitter tip by the number of triodes in parallel or in the bank while the series arrangement increases gain. The term "bank" is utilized to describe a plurality of parallel triodes which essentially are arranged in a bank or other configuration. The construction of such triodes utilizing integrated circuit techniques is extremely well known in the prior art and many examples exist as indicated by the above references. The use of parallel outputs which are combined to increase the overall current is also well known in the art as can be ascertained by many references. See, for example, an article entitled "Field Emission Cathode Array Development for High Current Density Applications" by C. A. Spindt, C. E. Holland, R. D. Stowell published in 1983 in Applied Surface Science, Vol. 16, Pages 268-276. The technique of paralleling tubes or triodes to increase current and power is a well known technique. See, for example, "Theory and Applications of Electron Tubes" published by McGraw-Hill Book Company, Inc., 1939 by H. J. Reich. In regard to this, multiple parallel tube arrangements were also known in the prior art and utilized conventional vacuum tubes. To obtain more power output, several tubes were used together if care was taken to suppress moding which tends to occur when some dimension of the combining circuitry used becomes large in terms of the wavelength. In any event, utilizing prior art techniques involve great difficulty. The physical geometries of the cathode, grid (gate) and plate affect the gain and the upper frequency limit. Other factors such as the coupling and biasing networks also had adverse effects on operation. Thus in such schemes, such as employing vertical schemes the biasing required was only specified on a schematic basis and the techniques do not address the manufacturing requirements. The lateral schemes utilize strip line interconnects that occupy a large portion of the array and thus decrease the array power density.
It is therefore an object of the present invention to provide a distributed array of microelectronic amplifiers which array enables the coupling of large numbers of microelectronic amplifiers without the problems attended in the prior art.
It is a further object of the present invention to provide a distributed triode bank array which constitutes a large power amplifier consisting of a plurality of microelectronic triodes.